(a) Field of the Invention
The present invention relates to an electronic musical instrument equipped with an automatic accompaniment system, and more particularly it concerns a system capable of randomly modifying memorized automatic accompaniment patterns during the progression of play of any one of the accompaniment patterns as it is read out from the memory means, on an electronic musical instrument, thus providing variation-rich automatic accompaniment.
(b) Description of the Prior Art
Known automatic accompaniment devices for use in electronic musical instruments are arranged so that a large number of accompaniment data constituting accompaniment patterns such as chord patterns and bass patterns has been stored in advance in memory means, and that the generation of such accompaniment tones as chord tones and bass tones is realized based on the accompaniment determination data read out in succession from this memory means in accordance with the progression of performance, and based also on the key depression informations delivered from the accompaniment keyboard.
In such a known automatic accompaniment device as mentioned above, however, a number of accompaniment patterns have been preliminarily stored in memory means in such a manner as to correspond to various rhythm patterns in one accompaniment pattern versus one rhythm pattern fashion.
In order to obviate such a drawback of the prior art, there has been proposed in the past an arrangement designed so that several modified accompaniment patterns associated with a fundamental accompaniment pattern are stored in memory means, so that the user selects desired ones of the stored modified patterns by manipulating selection switches provided on the panel board of the instrument, and the accompaniment is now switched over to his desired modified pattern. In this known automatic accompaniment apparatus, however, there has been the inconvenience that, as the number of such modified patterns increases, the capacity of the memory means of accompaniment patterns also has to be increased accordingly.